The present invention relates to a vacuum type brake booster for use in a brake mechanism of a motor vehicle.
One of the conventional brake boosters of the kind is disclosed in the U.S. Pat. No. 4,800,799 issued on Jan. 31, 1989. The conventional brake booster has a function wherein its operating condition is set to be held despite the release of the input rod. This function serves for the driver's easy brake operation.
In the conventional brake booster, a depression a brake pedal is required for operating the input rod. After a time which is required for the depression of the brake pedal, the desired brake operation is established. This means that it is difficult to realize a quick or emergency brake operation for the conventional brake booster.